Abstract P227: Gq Signaling In The Placental Syncytiotrophoblast Layer During Preeclampsia

Hypertension ◽  
2021 ◽  
Vol 78 (Suppl_1) ◽  
Author(s):  
Megan Opichka ◽  
Mary Christine Livergood ◽  
Curt D Sigmund ◽  
Jennifer McIntosh ◽  
Justin L Grobe
Keyword(s):  
Cell Types ◽  
G Protein Signaling ◽  
Protein Signaling ◽  
Junctional Zone ◽  
Hybridization Data ◽  
Relative Change ◽  
Pathological Consequence ◽  
Syncytiotrophoblast Layer ◽  
Specific Deletion

Hormones implicated in preeclampsia (PE) such as angiotensin, endothelin, and vasopressin signal via receptors coupled to the Gq cascade, and Regulator of G protein Signaling-2 (RGS2) buffers this signaling. We have published that RGS2 expression is decreased in human PE placenta, and reducing RGS2 in placenta causes development of key features of PE in mice. New in situ hybridization data indicate that in both humans and mice, RGS2 is abundant among many cell types in the placenta, including the syncytiotrophoblast (STB) layer. In addition, RGS2 expression in the human STB layer is reduced during PE. As this layer is strongly implicated in PE, these data lead us to hypothesize a critical Gq-buffering role for RGS2 in STB cells to prevent PE. To explore the effect of excess Gq signaling within the STB layer, we utilized a Cre-Lox approach to cause expression of the Gq-coupled hM3Dq DREADD throughout the fetoplacental unit (dam: hM3Dq+, sire: Actb-Cre+) or only within the STB layer (dam: hM3Dq+, sire: Gcm1-Cre+), and then activated the hM3Dq receptor via clozapine N-oxide (CNO, 0.5 to 2 mg/kg) injection in mid-gestation (GD12.5-14.5) before tissue collection at GD14.5. Gαq activation throughout the fetoplacental unit (Actb-Cre model) severely restricted fetoplacental growth compared to saline-injected controls (n=2 vs 3; placenta: 0.027±0.006 vs 0.115±0.021 g; p<0.05, and fetus: 0.048±0.007 vs 0.268±0.010 g; p<0.05). Similarly, placentas expressing hM3Dq only in STB cells (Gcm1-Cre model) had reduced placental (n=3 0.116±0.022 vs 0.201±0.036 g; p=0.05) and possibly fetal (n=3 0.1112±0.036 vs 0.247±0.028 g; p=0.06) masses after CNO. Vascularization (assessed by CD31 immunostain) was disproportionately reduced in the labyrinth layer of the Actb-Cre model after CNO (n=2 vs 3; 20.189±3.382 vs 35.762±1.976 % area; p<0.05), despite no relative change in layer (ie, decidua/junctional zone/labyrinth) thicknesses. Preliminary results indicate similar findings in the Gcm1-Cre model (n=1 17 vs 25 % area). These data highlight the pathological consequence of excess Gq signaling in the STB layer. Ongoing studies are aimed at characterizing maternal phenotypes in these models and the consequence of STB-specific deletion of RGS2 upon sensitivity to Gq stimulators.

scholarly journals Tanycyte-independent control of hypothalamic leptin signaling

2019 ◽  
Author(s):  
Sooyeon Yoo ◽  
David Cha ◽  
Dong Won Kim ◽  
Thanh V. Hoang ◽  
Seth Blackshaw
Keyword(s):  
Gene Expression ◽  
Single Molecule ◽  
Leptin Receptor ◽  
Cell Types ◽  
Leptin Signaling ◽  
And Function ◽  
Induced Changes ◽  
The Brain ◽  
Specific Deletion

AbstractLeptin is secreted by adipocytes to regulate appetite and body weight. Recent studies have reported that tanycytes actively transport circulating leptin across the brain barrier into the hypothalamus, and are required for normal levels of hypothalamic leptin signaling. However, direct evidence for leptin receptor (LepR) expression is lacking, and the effect of tanycyte-specific deletion of LepR has not been investigated. In this study, we analyze the expression and function of the tanycytic LepR in mice. Using single-molecule fluorescent in situ hybridization (smfISH), RT-qPCR, single-cell RNA sequencing (scRNA-Seq), and selective deletion of the LepR in tanycytes, we are unable to detect expression of LepR in the tanycytes. Tanycyte-specific deletion of LepR likewise did not affect leptin-induced pSTAT3 expression in hypothalamic neurons, regardless of whether leptin was delivered by intraperitoneal or intracerebroventricular injection. Finally, we use activity-regulated scRNA-Seq (act-Seq) to comprehensively profile leptin-induced changes in gene expression in all cell types in mediobasal hypothalamus. Clear evidence for leptin signaling is only seen in endothelial cells and subsets of neurons, although virtually all cell types show leptin-induced changes in gene expression. We thus conclude that LepR expression in tanycytes is either absent or undetectably low, that tanycytes do not directly regulate hypothalamic leptin signaling through a LepR-dependent mechanism, and that leptin regulates gene expression in diverse hypothalamic cell types through both direct and indirect mechanisms.

scholarly journals Systematic analysis of expression signatures of neuronal subpopulations in the VTA

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Hyun Jin Kim ◽  
Minhyung Kim ◽  
Byeongsoo Kang ◽  
Soyeon Yun ◽  
Shin Eun Ryeo ◽  
...  
Keyword(s):  
Brain Area ◽  
Glutamate Transporter ◽  
Cell Types ◽  
Brain Atlas ◽  
Specific Cell ◽  
Systematic Analysis ◽  
Functional Roles ◽  
Hybridization Data ◽  
Specific Distribution

AbstractGene expression profiling across various brain areas at the single-cell resolution enables the identification of molecular markers of neuronal subpopulations and comprehensive characterization of their functional roles. Despite the scientific importance and experimental versatility, systematic methods to analyze such data have not been established yet. To this end, we developed a statistical approach based on in situ hybridization data in the Allen Brain Atlas and thereby identified specific genes for each type of neuron in the ventral tegmental area (VTA). This approach also allowed us to demarcate subregions within the VTA comprising specific neuronal subpopulations. We further identified WW domain-containing oxidoreductase as a molecular marker of a population of VTA neurons that co-express tyrosine hydroxylase and vesicular glutamate transporter 2, and confirmed their region-specific distribution by immunohistochemistry. The results demonstrate the utility of our analytical approach for uncovering expression signatures representing specific cell types and neuronal subpopulations enriched in a given brain area.

scholarly journals Regulator of G Protein Signaling 2 Deficiency Causes Endothelial Dysfunction and Impaired Endothelium-derived Hyperpolarizing Factor-mediated Relaxation by Dysregulating Gi/o Signaling

2012 ◽  
Vol 287 (15) ◽  
pp. 12541-12549 ◽  
Author(s):  
Patrick Osei-Owusu ◽  
Rasna Sabharwal ◽  
Kevin M. Kaltenbronn ◽  
Man-Hee Rhee ◽  
Mark W. Chapleau ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Endothelial Dysfunction ◽  
Vascular Smooth Muscle ◽  
G Protein ◽  
Peripheral Resistance ◽  
G Protein Signaling ◽  
Protein Signaling ◽  
Resistance Arteries ◽  
Contraction And Relaxation ◽  
Specific Deletion

Regulator of G protein signaling 2 (RGS2) is a GTPase-activating protein for Gq/11α and Gi/oα subunits. RGS2 deficiency is linked to hypertension in mice and humans, although causative mechanisms are not understood. Because endothelial dysfunction and increased peripheral resistance are hallmarks of hypertension, determining whether RGS2 regulates microvascular reactivity may reveal mechanisms relevant to cardiovascular disease. Here we have determined the effects of systemic versus endothelium- or vascular smooth muscle-specific deletion of RGS2 on microvascular contraction and relaxation. Contraction and relaxation of mesenteric resistance arteries were analyzed in response to phenylephrine, sodium nitroprusside, or acetylcholine with or without inhibitors of nitric oxide (NO) synthase or K+ channels that mediate endothelium-derived hyperpolarizing factor (EDHF)-dependent relaxation. The results showed that deleting RGS2 in vascular smooth muscle had minor effects. Systemic or endothelium-specific deletion of RGS2 strikingly inhibited acetylcholine-evoked relaxation. Endothelium-specific deletion of RGS2 had little effect on NO-dependent relaxation but markedly impaired EDHF-dependent relaxation. Acute, inducible deletion of RGS2 in endothelium did not affect blood pressure significantly. Impaired EDHF-mediated vasodilatation was rescued by blocking Gi/oα activation with pertussis toxin. These findings indicated that systemic or endothelium-specific RGS2 deficiency causes endothelial dysfunction resulting in impaired EDHF-dependent vasodilatation. RGS2 deficiency enables endothelial Gi/o activity to inhibit EDHF-dependent relaxation, whereas RGS2 sufficiency facilitates EDHF-evoked relaxation by squelching endothelial Gi/o activity. Mutation or down-regulation of RGS2 in hypertension patients therefore may contribute to endothelial dysfunction and defective EDHF-dependent relaxation. Blunting Gi/o signaling might improve endothelial function in such patients.

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